GMPE specific average velocity profiles for developing spatially-varying path coefficients

Kathryn E. Wooddell, Linda Al Atik, & Norman A. Abrahamson

Published August 13, 2018, SCEC Contribution #8425, 2018 SCEC Annual Meeting Poster #026

CyberShake simulations are being run to develop spatially-varying path coefficients in regions of sparse coverage that lack sufficient recorded earthquake ground motion data.  The methodology for calculating the coefficients requires both 3D and 1D CyberShake simulations to remove the ergodic portion of the path effect and center the model on the GMPE following the approach of Wooddell and Abrahamson (2017).  A preliminary attempt was made at this using a 1D velocity model that was a smoothed version of the available 3D velocity model.  The idea was to use this model along with a correction factor to center it on the GMPE.  However, an analysis of the currently available 1D simulations revealed that the 1D velocity model is insufficient for this application because it contains non-ergodic features that are not present in the GMPEs. Therefore, we develop a GMPE-specific 1D velocity model using the ASK14 model to allow us to proceed with this approach. The empirical Fourier Amplitude Spectrum (FAS) model (Bayless and Abrahamson, 2018) is used to compute the frequency-dependent linear site amplification factors for different Vs30 ranges. These factors are then used to remove the average kappa scaling and inverted to develop an average 1D velocity model for ASK14. This 1D velocity model is a representative of the average velocity profiles in the ASK14 dataset and will be run on the CyberShake platform and used to develop spatially-varying path coefficients.

Key Words
nonergodic, CCSP, CyberShake, FAS, empirical FAS, nonergodic GMPE, ground-motion models, spatially varying coefficients

Citation
Wooddell, K. E., Al Atik, L., & Abrahamson, N. A. (2018, 08). GMPE specific average velocity profiles for developing spatially-varying path coefficients. Poster Presentation at 2018 SCEC Annual Meeting.

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